Ideal and Non-ideal solutions

 Ideal and Non-ideal solutions

Ideal solutions :What is an ideal solution in chemistry?

(In chemistry, an ideal solution or ideal mixture is a solution with thermodynamic properties analogous to those of a mixture of ideal gases. ... The vapor pressure of the solution obeys Raoult's law, and the activity coefficient of each component (which measures deviation from ideality) is equal to one)
An ideal solution is the solution in which each component obeys Raoult’s law under all conditions of temperatures and concentrations.

Properties of Ideal solutions :

ΔH_MIXING = 0

ΔV_MIXING = 0

Intermolecular attractive forces between the A-A and B-B are nearly equal to those between A-B. 
Eg. solution of benzene and toluene, solution of n-hexane and n-heptane

Non – ideal solutions :What is an Non- ideal solution in chemistry?

(A non-ideal solution is a solution whose properties are generally not very predictable on account of the intermolecular forces between the molecules. None.Non-ideal solutions by definition cannot be dealt with through Raoult's Law. Raoult's Law is strictly forideal solutions only. A non-ideal solution)
 When a solution does not obey Raoult’s law over the entire range of concentration, then it is called non-ideal solution.

Solutions showing positive deviation from Raoult’s Law :

Solvent-Solute(A-B) type of force is weaker than Solute-Solute (B-B) &  Solvent-Solvent(A-A) forces.

The vapour pressure is higher than predicted by the law

ΔH_MIXING > 0

ΔV_MIXING > 0

Eg. ethanol and acetone, carbon disulphide and acetone 

Solutions showing negative deviations from Raoult’s law :

1. Solvent-Solute(A-B) type of force is stronger than the other two.
2. The vapour pressure is lower than predicted by the law.
3. ΔH_MIXING < 0
4. ΔV_MIXING < 0

For example,phenol and aniline, chloroform and acetone etc 

What is meant by azeotropic mixture?

An azeotrope (UK /əˈziːəˌtrəʊp/, US /əˈziəˌtroʊp/) or a constant boiling pointmixture is a mixture of two or more liquids whose proportions cannot be altered or changed by simple distillation. This happens because when an azeotrope is boiled, the vapour has the same proportions of constituents as the unboiled mixture.